1. Field of the Invention
The present invention relates to an electronic device, and more particularly to an electrically refrigerated electronic device in which an electronic device is freezed by using electricity.
2. Description of the Related Art
For example, radiation detecting semiconductor device for detecting radioactive rays with a cooled semiconductor detecting element are widely used not only for measuring radioactive rays such as gamma rays and X-rays radiated at nuclear reactor facilities but also in the fields of radiation instrumentation such as nuclear physics, astro-physics, and nuclear chemistry. Cooling is an effective means for reducing noises in electronic devices which deal with weak signals. Cooling is generally performed by using refrigerant such as liquid nitrogen.
FIG. 14 shows a conventionally used radiation detecting semiconductor device of a liquid nitrogen type. A refrigerant vessel 102 disposed in a vacuum housing 109 contains liquid nitrogen 103. A cooling rod 104 extends from the side wall of the cooling vessel 102 and enters the inside of a pipe 108 mounted on the side wall of the vacuum housing 109 and passes through a flange 107. A radiation detecting semiconductor element 101 is mounted on the tip end of the cooling rod 104. A vacuum container 105 is hermetically mounted on the flange 107 and constitutes a vacuum chamber together with the vacuum housing 109. The cooling rod 104 and radiation detecting semiconductor element 101 are in the vacuum container. The radiation detecting semiconductor element 101 is cooled by the cooling rod 104 approximately down to the liquid nitrogen temperature.
A preamplifer 106 is installed on the side wall of the pipe 108. A radiation detection signal outputted from the radiation detecting semiconductor element 101 is inputted via lead wires L to the preamplifier 106. The preamplifier 106 amplifies the inputted radiation detection signal and outputs it to a radiation signal detector circuit of a later stage.
FIG. 15 shows a conventional radiation detecting semiconductor device using a closed cycle tie cooler. A compressor 110 is connected via pipes 111 to an adiabatic compression part 112. A cylinder 116 extends in a pipe 113 connected to the adiabatic compression part 112. A radiation detecting semiconductor element 101 is mounted via a buffer 115 on an adiabatic expansion part (cooling part) 114 at an end of the cylinder 116.
A vacuum container 105 is mounted via a flange to the end portion of the pipe 113. The radiation detecting semiconductor element 101, buffer 115, and cylinder 116 are hermetically housed in the vacuum container 105. Compressed He gas is allowed to adiabatically expand in the cooling part 114 so that it is cooled. The radiation detecting semiconductor element 101 is also cooled via the buffer 115.
A preamplifier 106 is mounted on the side wall of the pipe 113. Similar to the device shown in FIG. 14, the preamplifier 106 amplifies a radiation detection signal and outputs the amplified signal to a radiation signal detector circuit of a later stage.
The radiation detecting semiconductor device of a liquid nitrogen cooling type shown in FIG. 14 uses liquid nitrogen for cooling a radiation detecting semiconductor element. It is necessary therefore to prepare liquid nitrogen for the detection of radiation. It is thus difficult to use the detecting device with ease, and the usable place of the device is restricted. A cooling vessel is a requisite for using the device so that it is difficult to make it compact.
Vibrations of the cooling part 114 of the closed cycle lie cooler shown in FIG. 15 are inevitable because of its mechanical structure. Vibrations of the cooling part 114 generate microphonic noises. These microphonic noises may become a cause of lowering energy resolution which is an important performance of the radiation detecting device.
The frequency range of microphonic noises extends near to the frequency of a radiation detection signal. It is therefore difficult to eliminate them by using only a signal processing technique. In order to alleviate the influence of microphonic noises, the buffer 115 is inserted between the cooling section 114 and radiation detecting semiconductor element 101. It is necessary to cool also the buffer 115 during the radiation measurement so that a large cooling capacity is needed.